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<title>The Lifecycles of Enterprise Beans - The Java EE 6 Tutorial</title>
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      <td width="400px"><p class="toc level1"><a href="docinfo.html">Document Information</a></p>
<p class="toc level1 tocsp"><a href="gexaf.html">Preface</a></p>
<p class="toc level1 tocsp"><a href="gfirp.html">Part&nbsp;I&nbsp;Introduction</a></p>
<p class="toc level2"><a href="bnaaw.html">1.&nbsp;&nbsp;Overview</a></p>
<p class="toc level2"><a href="gfiud.html">2.&nbsp;&nbsp;Using the Tutorial Examples</a></p>
<p class="toc level1 tocsp"><a href="bnadp.html">Part&nbsp;II&nbsp;The Web Tier</a></p>
<p class="toc level2"><a href="bnadr.html">3.&nbsp;&nbsp;Getting Started with Web Applications</a></p>
<p class="toc level2"><a href="bnaph.html">4.&nbsp;&nbsp;JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="giepx.html">5.&nbsp;&nbsp;Introduction to Facelets</a></p>
<p class="toc level2"><a href="gjddd.html">6.&nbsp;&nbsp;Expression Language</a></p>
<p class="toc level2"><a href="bnaqz.html">7.&nbsp;&nbsp;Using JavaServer Faces Technology in Web Pages</a></p>
<p class="toc level2"><a href="gjcut.html">8.&nbsp;&nbsp;Using Converters, Listeners, and Validators</a></p>
<p class="toc level2"><a href="bnatx.html">9.&nbsp;&nbsp;Developing with JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="gkmaa.html">10.&nbsp;&nbsp;JavaServer Faces Technology Advanced Concepts</a></p>
<p class="toc level2"><a href="bnawo.html">11.&nbsp;&nbsp;Configuring JavaServer Faces Applications</a></p>
<p class="toc level2"><a href="gkiow.html">12.&nbsp;&nbsp;Using Ajax with JavaServer Faces Technology</a></p>
<p class="toc level2"><a href="gkhxa.html">13.&nbsp;&nbsp;Advanced Composite Components</a></p>
<p class="toc level2"><a href="bnavg.html">14.&nbsp;&nbsp;Creating Custom UI Components</a></p>
<p class="toc level2"><a href="bnafd.html">15.&nbsp;&nbsp;Java Servlet Technology</a></p>
<p class="toc level2"><a href="bnaxu.html">16.&nbsp;&nbsp;Internationalizing and Localizing Web Applications</a></p>
<p class="toc level1 tocsp"><a href="bnayk.html">Part&nbsp;III&nbsp;Web Services</a></p>
<p class="toc level2"><a href="gijti.html">17.&nbsp;&nbsp;Introduction to Web Services</a></p>
<p class="toc level2"><a href="bnayl.html">18.&nbsp;&nbsp;Building Web Services with JAX-WS</a></p>
<p class="toc level2"><a href="giepu.html">19.&nbsp;&nbsp;Building RESTful Web Services with JAX-RS</a></p>
<p class="toc level2"><a href="gjjxe.html">20.&nbsp;&nbsp;Advanced JAX-RS Features</a></p>
<p class="toc level2"><a href="gkojl.html">21.&nbsp;&nbsp;Running the Advanced JAX-RS Example Application</a></p>
<p class="toc level1 tocsp"><a href="bnblr.html">Part&nbsp;IV&nbsp;Enterprise Beans</a></p>
<p class="toc level2"><a href="gijsz.html">22.&nbsp;&nbsp;Enterprise Beans</a></p>
<p class="toc level3"><a href="gipmb.html">What Is an Enterprise Bean?</a></p>
<p class="toc level4"><a href="gipmb.html#giplk">Benefits of Enterprise Beans</a></p>
<p class="toc level4"><a href="gipmb.html#gipkn">When to Use Enterprise Beans</a></p>
<p class="toc level4"><a href="gipmb.html#gipnm">Types of Enterprise Beans</a></p>
<p class="toc level3 tocsp"><a href="gipjg.html">What Is a Session Bean?</a></p>
<p class="toc level4"><a href="gipjg.html#gipkr">Types of Session Beans</a></p>
<p class="toc level5"><a href="gipjg.html#gipnl">Stateful Session Beans</a></p>
<p class="toc level5"><a href="gipjg.html#gipin">Stateless Session Beans</a></p>
<p class="toc level5"><a href="gipjg.html#gipim">Singleton Session Beans</a></p>
<p class="toc level4 tocsp"><a href="gipjg.html#gipmt">When to Use Session Beans</a></p>
<p class="toc level3 tocsp"><a href="gipko.html">What Is a Message-Driven Bean?</a></p>
<p class="toc level4"><a href="gipko.html#gipmj">What Makes Message-Driven Beans Different from Session Beans?</a></p>
<p class="toc level4"><a href="gipko.html#gipjx">When to Use Message-Driven Beans</a></p>
<p class="toc level3 tocsp"><a href="gipjf.html">Accessing Enterprise Beans</a></p>
<p class="toc level4"><a href="gipjf.html#girfl">Using Enterprise Beans in Clients</a></p>
<p class="toc level5"><a href="gipjf.html#girgn">Portable JNDI Syntax</a></p>
<p class="toc level4 tocsp"><a href="gipjf.html#gipiz">Deciding on Remote or Local Access</a></p>
<p class="toc level4"><a href="gipjf.html#gipmz">Local Clients</a></p>
<p class="toc level5"><a href="gipjf.html#gipsc">Accessing Local Enterprise Beans Using the No-Interface View</a></p>
<p class="toc level5"><a href="gipjf.html#gipse">Accessing Local Enterprise Beans That Implement Business Interfaces</a></p>
<p class="toc level4 tocsp"><a href="gipjf.html#gipiu">Remote Clients</a></p>
<p class="toc level4"><a href="gipjf.html#gipkd">Web Service Clients</a></p>
<p class="toc level4"><a href="gipjf.html#giply">Method Parameters and Access</a></p>
<p class="toc level5"><a href="gipjf.html#giplx">Isolation</a></p>
<p class="toc level5"><a href="gipjf.html#gipkv">Granularity of Accessed Data</a></p>
<p class="toc level3 tocsp"><a href="gipio.html">The Contents of an Enterprise Bean</a></p>
<p class="toc level4"><a href="gipio.html#gipnz">Packaging Enterprise Beans in EJB JAR Modules</a></p>
<p class="toc level4"><a href="gipio.html#gippi">Packaging Enterprise Beans in WAR Modules</a></p>
<p class="toc level3 tocsp"><a href="gipks.html">Naming Conventions for Enterprise Beans</a></p>
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<p class="toc level3"><a href="">The Lifecycles of Enterprise Beans</a></p>
<p class="toc level4"><a href="#gipln">The Lifecycle of a Stateful Session Bean</a></p>
<p class="toc level4"><a href="#giplm">The Lifecycle of a Stateless Session Bean</a></p>
<p class="toc level4"><a href="#giprx">The Lifecycle of a Singleton Session Bean</a></p>
<p class="toc level4"><a href="#gipkw">The Lifecycle of a Message-Driven Bean</a></p>
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<p class="toc level3 tocsp"><a href="giplg.html">Further Information about Enterprise Beans</a></p>
<p class="toc level2 tocsp"><a href="gijre.html">23.&nbsp;&nbsp;Getting Started with Enterprise Beans</a></p>
<p class="toc level2"><a href="gijrb.html">24.&nbsp;&nbsp;Running the Enterprise Bean Examples</a></p>
<p class="toc level2"><a href="bnbpk.html">25.&nbsp;&nbsp;A Message-Driven Bean Example</a></p>
<p class="toc level2"><a href="gkcqz.html">26.&nbsp;&nbsp;Using the Embedded Enterprise Bean Container</a></p>
<p class="toc level2"><a href="gkidz.html">27.&nbsp;&nbsp;Using Asynchronous Method Invocation in Session Beans</a></p>
<p class="toc level1 tocsp"><a href="gjbnr.html">Part&nbsp;V&nbsp;Contexts and Dependency Injection for the Java EE Platform</a></p>
<p class="toc level2"><a href="giwhb.html">28.&nbsp;&nbsp;Introduction to Contexts and Dependency Injection for the Java EE Platform</a></p>
<p class="toc level2"><a href="gjbls.html">29.&nbsp;&nbsp;Running the Basic Contexts and Dependency Injection Examples</a></p>
<p class="toc level2"><a href="gjehi.html">30.&nbsp;&nbsp;Contexts and Dependency Injection for the Java EE Platform: Advanced Topics</a></p>
<p class="toc level2"><a href="gkhre.html">31.&nbsp;&nbsp;Running the Advanced Contexts and Dependency Injection Examples</a></p>
<p class="toc level1 tocsp"><a href="bnbpy.html">Part&nbsp;VI&nbsp;Persistence</a></p>
<p class="toc level2"><a href="bnbpz.html">32.&nbsp;&nbsp;Introduction to the Java Persistence API</a></p>
<p class="toc level2"><a href="gijst.html">33.&nbsp;&nbsp;Running the Persistence Examples</a></p>
<p class="toc level2"><a href="bnbtg.html">34.&nbsp;&nbsp;The Java Persistence Query Language</a></p>
<p class="toc level2"><a href="gjitv.html">35.&nbsp;&nbsp;Using the Criteria API to Create Queries</a></p>
<p class="toc level2"><a href="gkjiq.html">36.&nbsp;&nbsp;Creating and Using String-Based Criteria Queries</a></p>
<p class="toc level2"><a href="gkjjf.html">37.&nbsp;&nbsp;Controlling Concurrent Access to Entity Data with Locking</a></p>
<p class="toc level2"><a href="gkjia.html">38.&nbsp;&nbsp;Improving the Performance of Java Persistence API Applications By Setting a Second-Level Cache</a></p>
<p class="toc level1 tocsp"><a href="gijrp.html">Part&nbsp;VII&nbsp;Security</a></p>
<p class="toc level2"><a href="bnbwj.html">39.&nbsp;&nbsp;Introduction to Security in the Java EE Platform</a></p>
<p class="toc level2"><a href="bncas.html">40.&nbsp;&nbsp;Getting Started Securing Web Applications</a></p>
<p class="toc level2"><a href="bnbyk.html">41.&nbsp;&nbsp;Getting Started Securing Enterprise Applications</a></p>
<p class="toc level1 tocsp"><a href="gijue.html">Part&nbsp;VIII&nbsp;Java EE Supporting Technologies</a></p>
<p class="toc level2"><a href="gijto.html">42.&nbsp;&nbsp;Introduction to Java EE Supporting Technologies</a></p>
<p class="toc level2"><a href="bncih.html">43.&nbsp;&nbsp;Transactions</a></p>
<p class="toc level2"><a href="bncjh.html">44.&nbsp;&nbsp;Resource Connections</a></p>
<p class="toc level2"><a href="bncdq.html">45.&nbsp;&nbsp;Java Message Service Concepts</a></p>
<p class="toc level2"><a href="bncgv.html">46.&nbsp;&nbsp;Java Message Service Examples</a></p>
<p class="toc level2"><a href="gkahp.html">47.&nbsp;&nbsp;Advanced Bean Validation Concepts and Examples</a></p>
<p class="toc level2"><a href="gkeed.html">48.&nbsp;&nbsp;Using Java EE Interceptors</a></p>
<p class="toc level1 tocsp"><a href="gkgjw.html">Part&nbsp;IX&nbsp;Case Studies</a></p>
<p class="toc level2"><a href="gkaee.html">49.&nbsp;&nbsp;Duke's Tutoring Case Study Example</a></p>
<p class="toc level1 tocsp"><a href="idx-1.html">Index</a></p>
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<a name="giplj"></a><h2>The Lifecycles of Enterprise Beans</h2>
<a name="indexterm-1380"></a><a name="indexterm-1381"></a><a name="indexterm-1382"></a><p>An enterprise bean goes through various stages during its lifetime, or lifecycle. Each
type of enterprise bean (stateful session, stateless session, singleton session, or message-driven) has
a different lifecycle.</p>

<p>The descriptions that follow refer to methods that are explained along with the
code examples in the next two chapters. If you are new to
enterprise beans, you should skip this section and run the code examples first.</p>



<a name="gipln"></a><h3>The Lifecycle of a Stateful Session Bean</h3>
<p><a href="#gipmi">Figure&nbsp;22-3</a> illustrates the stages that a session bean passes through during its lifetime.
The client initiates the lifecycle by obtaining a reference to a stateful session
bean. The container performs any dependency injection and then invokes the method annotated with
<tt>@PostConstruct</tt>, if any. The bean is now ready to have its business methods
invoked by the client.</p>

<a name="gipmi"></a><p class="caption">Figure&nbsp;22-3 Lifecycle of a Stateful Session Bean</p><a name="indexterm-1383"></a><img src="figures/ejbcon-statefulSessionBeanLifeCycle.gif" alt="Diagram showing the lifecycle of a stateful session bean."></img><p><a name="indexterm-1384"></a><a name="indexterm-1385"></a>While in the ready stage, the EJB container may decide to deactivate, or
<b>passivate</b>, the bean by moving it from memory to secondary storage. (Typically, the
EJB container uses a least-recently-used algorithm to select a bean for passivation.) The
EJB container invokes the method annotated <tt>@PrePassivate</tt>, if any, immediately before passivating it. If
a client invokes a business method on the bean while it is in
the passive stage, the EJB container activates the bean, calls the method annotated
<tt>@PostActivate</tt>, if any, and then moves it to the ready stage.</p>

<p>At the end of the lifecycle, the client invokes a method annotated
<tt>@Remove</tt>, and the EJB container calls the method annotated <tt>@PreDestroy</tt>, if any.
The bean&rsquo;s instance is then ready for garbage collection.</p>

<p>Your code controls the invocation of only one lifecycle method: the method annotated
<tt>@Remove</tt>. All other methods in <a href="#gipmi">Figure&nbsp;22-3</a> are invoked by the EJB container. See
<a href="bncjh.html">Chapter&nbsp;44, Resource Connections</a> for more information.</p>



<a name="giplm"></a><h3>The Lifecycle of a Stateless Session Bean</h3>
<p>Because a stateless session bean is never passivated, its lifecycle has only two
stages: nonexistent and ready for the invocation of business methods. <a href="#gipni">Figure&nbsp;22-4</a> illustrates the stages
of a stateless session bean.</p>

<a name="gipni"></a><p class="caption">Figure&nbsp;22-4 Lifecycle of a Stateless Session Bean</p><img src="figures/ejbcon-statelessSessionBeanLifeCycle.gif" alt="Diagram showing the lifecycle of a stateless session bean."></img><p>The EJB container typically creates and maintains a pool of stateless session beans,
beginning the stateless session bean&rsquo;s lifecycle. The container performs any dependency injection and
then invokes the method annotated <tt>@PostConstruct</tt>, if it exists. The bean is
now ready to have its business methods invoked by a client.</p>

<p>At the end of the lifecycle, the EJB container calls the method
annotated <tt>@PreDestroy</tt>, if it exists. The bean&rsquo;s instance is then ready for garbage
collection.</p>



<a name="giprx"></a><h3>The Lifecycle of a Singleton Session Bean</h3>
<p>Like a stateless session bean, a singleton session bean is never passivated and
has only two stages, nonexistent and ready for the invocation of business methods,
as shown in <a href="#gippc">Figure&nbsp;22-5</a>.</p>

<a name="gippc"></a><p class="caption">Figure&nbsp;22-5 Lifecycle of a Singleton Session Bean</p><img src="figures/ejbcon-statelessSessionBeanLifeCycle.gif" alt="Diagram showing the lifecycle of a singleton session bean."></img><p>The EJB container initiates the singleton session bean lifecycle by creating the singleton
instance. This occurs upon application deployment if the singleton is annotated with the
<tt>@Startup</tt> annotation The container performs any dependency injection and then invokes the method annotated
<tt>@PostConstruct</tt>, if it exists. The singleton session bean is now ready to have
its business methods invoked by the client.</p>

<p>At the end of the lifecycle, the EJB container calls the method
annotated <tt>@PreDestroy</tt>, if it exists. The singleton session bean is now ready for
garbage collection.</p>



<a name="gipkw"></a><h3>The Lifecycle of a Message-Driven Bean</h3>
<p><a href="#giplr">Figure&nbsp;22-6</a> illustrates the stages in the lifecycle of a message-driven bean.</p>

<a name="giplr"></a><p class="caption">Figure&nbsp;22-6 Lifecycle of a Message-Driven Bean</p><img src="figures/ejbcon-messageDrivenBeanLifeCycle.gif" alt="Diagram showing the lifecycle of a message-driven bean."></img><p>The EJB container usually creates a pool of message-driven bean instances. For each
instance, the EJB container performs these tasks.</p>


<ol><li><p>If the message-driven bean uses dependency injection, the container injects these references before instantiating the instance.</p>

</li>
<li><p>The container calls the method annotated <tt>@PostConstruct</tt>, if any.</p>

</li></ol>
<p>Like a stateless session bean, a message-driven bean is never passivated and has
only two states: nonexistent and ready to receive messages.</p>

<p><a name="indexterm-1386"></a><a name="indexterm-1387"></a>At the end of the lifecycle, the container calls the method annotated
<tt>@PreDestroy</tt>, if any. The bean&rsquo;s instance is then ready for garbage collection.</p>


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